Electronic display devices have been widely used in various electronic appliances, such as a liquid crystal television, a liquid crystal display, a digital poster board, a laptop computer, a personal digital assistance (PDA), a mobile phone, a digital camera and an electronic book reader. Previously, a flat display, such as a flat television and a flat liquid crystal display, was dominant among display devices. However, a display effect of the flat display is not perfect, because visual angles corresponding to line segments of the same length displayed on the flat display are different no matter where a viewer is in front of the flat display, and hence the viewer perceives that the line segments have different lengths. A curved-surface display has been proposed, and a difference between the curved-surface display (such as, a curved-surface television) and the flat display is that: for a viewer at a proper position, the visual angles for objects of a unit length displayed on the curved-surface display are identical to each other, while the visual angles for the objects of a unit length displayed on the flat display are different. Therefore, the display effect of the flat display is inferior to that of the curved-surface display. Due to difficulties in the process for manufacturing the curved-surface display, the manufacturing cost of the existing curved-surface display is rather expensive.